1. Keep the walls clean and dry. 2. Apply tape to the crack and press it tightly. 3. Confirm that the gap has been covered with tape, then cut off the excess tape with a knife, and finally brush it with mortar. 4. Let it air dry naturally, then gently polish it. 5. Fill enough paint to make its surface smooth. 6. Cut off the leaked tape. Then, note that all cracks have been properly repaired, and use fine composite materials to decorate the area around the repair to make it as smooth as new. I hope it can help you